diff --git a/src/bundle.ts b/src/bundle.ts
index bca3270e..3862ad08 100644
--- a/src/bundle.ts
+++ b/src/bundle.ts
@@ -8,6 +8,7 @@ import fs from 'fs'
 import { resolve } from 'path'
 import { createOutputState } from './plugins/output-state-plugin'
 import {
+  fileExists,
   getPackageMeta,
   getSourcePathFromExportPath,
   isTypescriptFile,
@@ -17,6 +18,7 @@ import type { BuildContext } from './types'
 import {
   TypescriptOptions,
   resolveTsConfig,
+  resolveTsConfigPath,
   writeDefaultTsconfig,
 } from './typescript'
 import { collectEntriesFromParsedExports } from './entries'
@@ -59,8 +61,10 @@ async function bundle(
   const inputFile = cliEntryPath
   const isFromCli = Boolean(cliEntryPath)
 
-  let tsConfig = resolveTsConfig(cwd, options.tsconfig)
+  const tsConfigPath = resolveTsConfigPath(cwd, options.tsconfig)
+  let tsConfig = resolveTsConfig(cwd, tsConfigPath)
   let hasTsConfig = Boolean(tsConfig?.tsConfigPath)
+
   const defaultTsOptions: TypescriptOptions = {
     tsConfigPath: tsConfig?.tsConfigPath,
     tsCompilerOptions: tsConfig?.tsCompilerOptions || {},
@@ -132,10 +136,16 @@ async function bundle(
   const hasTypeScriptFiles = Object.values(entries).some((entry) =>
     isTypescriptFile(entry.source),
   )
+  // If there's no tsconfig, create one.
   if (hasTypeScriptFiles && !hasTsConfig) {
-    const tsConfigPath = resolve(cwd, 'tsconfig.json')
-    defaultTsOptions.tsConfigPath = tsConfigPath
-    await writeDefaultTsconfig(tsConfigPath)
+    // Check if tsconfig.json exists in the project first.
+    // If not, create one with default settings.
+    // Otherwise, use the existing one.
+    const defaultTsConfigPath = resolve(cwd, 'tsconfig.json')
+    if (!fileExists(defaultTsConfigPath)) {
+      defaultTsOptions.tsConfigPath = defaultTsConfigPath
+      await writeDefaultTsconfig(defaultTsConfigPath)
+    }
     hasTsConfig = true
   }
 
diff --git a/src/lib/memoize.ts b/src/lib/memoize.ts
index 40914aaf..64e113d3 100644
--- a/src/lib/memoize.ts
+++ b/src/lib/memoize.ts
@@ -1,6 +1,6 @@
 type CacheKeyResolver = string | ((...args: any[]) => string)
 
-const memoize = <T extends (...args: any[]) => any>(
+const createMemoize = <T extends (...args: any[]) => any>(
   fn: T,
   cacheKey?: CacheKeyResolver, // if you need specify a cache key
   cacheArg?: Map<string, ReturnType<T>>,
@@ -24,5 +24,8 @@ const memoize = <T extends (...args: any[]) => any>(
 
 export const memoizeByKey = <T extends (...args: any[]) => any>(fn: T) => {
   const cache = new Map<string, ReturnType<T>>()
-  return (cacheKey?: CacheKeyResolver) => memoize(fn, cacheKey, cache)
+  return (cacheKey?: CacheKeyResolver) => createMemoize(fn, cacheKey, cache)
 }
+
+export const memoize = <T extends (...args: any[]) => any>(fn: T) =>
+  createMemoize(fn)
diff --git a/src/typescript.ts b/src/typescript.ts
index 3a228477..79ecac21 100644
--- a/src/typescript.ts
+++ b/src/typescript.ts
@@ -4,7 +4,7 @@ import { promises as fsp } from 'fs'
 import { Module } from 'module'
 import pc from 'picocolors'
 import { exit, fileExists } from './utils'
-import { memoizeByKey } from './lib/memoize'
+import { memoize } from './lib/memoize'
 import { DEFAULT_TS_CONFIG } from './constants'
 import { logger } from './logger'
 
@@ -38,14 +38,23 @@ function resolveTypescript(cwd: string): typeof import('typescript') {
   return ts
 }
 
+export const resolveTsConfigPath = memoize(
+  (
+    cwd: string,
+    tsconfigFileName: string | undefined = 'tsconfig.json',
+  ): string | undefined => {
+    let tsConfigPath: string | undefined
+    tsConfigPath = resolve(cwd, tsconfigFileName)
+    return fileExists(tsConfigPath) ? tsConfigPath : undefined
+  },
+)
+
 function resolveTsConfigHandler(
   cwd: string,
-  tsconfig = 'tsconfig.json',
+  tsConfigPath: string | undefined,
 ): null | TypescriptOptions {
   let tsCompilerOptions: CompilerOptions = {}
-  let tsConfigPath: string | undefined
-  tsConfigPath = resolve(cwd, tsconfig)
-  if (fileExists(tsConfigPath)) {
+  if (tsConfigPath) {
     // Use the original ts handler to avoid memory leak
     const ts = resolveTypescript(cwd)
     const basePath = tsConfigPath ? dirname(tsConfigPath) : cwd
@@ -64,7 +73,7 @@ function resolveTsConfigHandler(
   }
 }
 
-export const resolveTsConfig = memoizeByKey(resolveTsConfigHandler)()
+export const resolveTsConfig = memoize(resolveTsConfigHandler)
 
 export async function convertCompilerOptions(cwd: string, json: any) {
   // Use the original ts handler to avoid memory leak
diff --git a/test/integration/tsconfig-override/index.test.ts b/test/integration/tsconfig-override/index.test.ts
index 102fdc85..d10490f2 100644
--- a/test/integration/tsconfig-override/index.test.ts
+++ b/test/integration/tsconfig-override/index.test.ts
@@ -4,6 +4,7 @@ describe('integration - tsconfig-override - default', () => {
   const { distDir } = createJob({
     directory: __dirname,
   })
+
   it('should use es5 output in build without override', async () => {
     await assertFilesContent(distDir, {
       ['index.js']: (content) => {
@@ -16,7 +17,7 @@ describe('integration - tsconfig-override - default', () => {
 describe('integration - tsconfig-override - customized', () => {
   const { distDir } = createJob({
     directory: __dirname,
-    args: ['--tsconfig', 'tsconfig.override.json'],
+    args: ['--tsconfig', 'tsconfig.build.json'],
   })
 
   it('should use es8 output in build', async () => {